Considerable progress has been made in the development of more effective regimens for the treatment of different types of solid cancers such as breast, colon, head and neck, malignant gliomas and glioblastoma, lung cancer, non-small cell lung cancer (NSCLC), melanoma, breast cancer, testicular cancer, carcinomas, sarcomas, lymphomas, pancreatic cancer, gastrointestinal stromal tumor, renal cancer, ovarian, prostate and others, and some leukemias such as chronic myeloid leukemia (CML).
Unfortunately, increased response rates to current chemotherapeutic and targeted therapy regimens have not been translated into marked improvements in survival since durations of response rates have been brief, and the natural history of the disease has ultimately remained unaltered. The development of drug resistance through amplification and development of new genes encoding protein kinases is a major obstacle to successful cancer therapy, given the important recent progress in treating different cancers through the use of multi-targeted kinase inhibitors. Great efforts have focused on the underlying mechanisms that turn promising targeted therapies which induce initial tumor shrinkage ineffective after a few months, resulting in refractory or untreatable cancers. Cytotoxic drugs are now used at some time during the course of the treatment of most cancer patients. Cytotoxic drugs can cure some primary and metastatic cancers and be effective in decreasing tumor volume, treating symptoms and even prolonging life in many types of cancers. However, survival rate has not been improved because these regimens are non-selective and related with systemic toxicities.
Therefore, molecular targeted therapy shows promise as an alternative treatment strategy since multiple molecular signaling pathways have been found to be dysregulated in most of the cancers such as breast, colon, head and neck, malignant gliomas and glioblastoma, lung cancer, NSCLC, melanoma, breast cancer, testicular cancer, carcinomas, sarcomas, lymphomas, renal cancer, pancreatic cancer, gastrointestinal stromal tumor, ovarian, prostate and others, and some leukemias such as chronic myeloid leukemia (CML).
Targeted therapy focuses on oncogenic signaling pathways specific to different cancers such as epidermal growth factor receptor (EGFR), human epidermal growth factor receptor 2 (HER-2), vascular endothelial growth factor receptor (VEGFR), insulin growth factor-1-receptor (IGF-1R), MET receptor, transcriptional factor nuclear factor kappa β (NF-kβ), KRAS, BRAF or phosphotidyl inositol-3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway.
Targeted therapy focuses on any one of the oncogenic signaling pathways in patients with a cancer whose tumors harbor a specific mutation, and includes therapy with the inhibitor of the tyrosine kinase(s) involved with the expression of the mutation. Initial tumor shrinkage is generally observed but the cancer progresses because it acquires resistance to the specific or multi-targeted tyrosine kinase inhibitor (TKI) used by acquiring mutations in other oncogenes. Such gene amplifications represent a major reason for treatment failure because the specific or multi-targeted tyrosine kinase inhibitor is ineffective against the newly developed mutations. In addition, some of the TKIs currently in use and available may not be successful in silencing the specific mutation found in the cancer and thus not only will the mutation remain untreated but the TKI may induce amplification of new mutations.
The use of multi-targeted kinase inhibitors for cancer therapy is attractive because one agent can inhibit multiple kinases. Examples of multi-targeted kinase inhibitors include sunitnib (VEGFs, platelet-derived growth factor-PDGF), sorafenib, dasatinib, lapatinib, among others. However, these compounds are not effective after some cycles of treatment when gene amplification and new mutations induce acquired resistance to them.
The present invention also provides a method to modulate early and late changes induced by the chemotherapeutic and targeted drugs in inducing new oncogenes and gene amplifications to circumvent the TKI or chemotherapy and thus to prevent the resistance to antitumor activity to achieve treatment success. More particularly, CTO is selected because it has demonstrated the ability to inhibit multiple TKI pathways in multiple types of targets. Bauer et al 2000; Alessandro et al 2008; Corrado et al, 2012.
Importantly, and unexpectedly, CTO was found to inhibit amplification of the genes induced by a variety of prior therapies, including the multi-targeted kinases inhibitors currently in use, and to restore response in refractory cancers even when administered alone in advanced cancer patients. Thus, CTO has the potential to treat serious malignant cancers by demonstrating substantial improvement over existing therapies on stabilizing and or inducing responses in life threatening refractory cancers.
The present invention provides a method for i) evaluating the effect of adding CTO to chemotherapeutic and/or targeted drugs on the responsiveness of a specific tumor type, ii) identifying any new gene mutations and/or mechanisms that induce the resistance to the previously effective therapeutic drugs, iii) administration of CTO to treat refractory cancers, selecting cancers that respond to CTO and designing a regimen of CTO plus chemotherapeutic and/or targeted drugs to prevent of inhibit and resume responsiveness, and iv) determining the pharmacodynamic interaction between the prior cytotoxic and/or targeted drugs and CTO to achieve maximum efficacy, least drug resistance and successful treatment.
In other words, the present invention provides a method to prevent or treat new oncogene mutations and known targetable oncogenes with CTO to inhibit multiple tyrosine kinase (TKI) signaling pathways and unknown TKIs, in multiple types of tumor targets, as found unexpectedly in clinical studies of CTO in patients with different types of refractory malignant cancers having a wide spectrum of genomic mutations in the respective tumor tissues and having been given prior chemotherapeutic and multi-targeted drugs. This effect of CTO is distinguished from that of multi-targeted kinase inhibitors currently in use, in that CTO inhibits multiple TKI pathways currently being targeted with current multi-targeted TKIs as well as other TKIs that may have resulted due to mutations or gene amplifications when current TKIs are used. This novel use of CTO was found in refractory cancers that had acquired resistance to drugs through new mutations and gene amplification.
CTO is an orotate salt of Carboxyamidotriazole (CAI). CAI is an inhibitor of receptor-operated calcium channel-mediated calcium influx, and is shown to have antiproliferative and anti-invasive functions in several human cancer cell lines, including human glioblastoma cells (Ge et al, 2000). By interrupting calcium mobilization as a second messenger, CAI can inhibit calcium-sensitive signal transduction pathways, including the release of arachidonic acid and its metabolites; nitric oxide release; the generation of inositol phosphates; and tyrosine phosphorylation (Ge et al, 2000; Kohn et al, 1992). CAI inhibits VEGF expression and secretion (Bauer et al, 2000). CAI inhibits phosphorylation of cellular proteins STATS and CrkL, and induces apoptosis in imatinib mesylate-resistant chronic myeloid leukemia cells by down-regulating bcr-abl (Alessandro et al, 2008). CTO inhibits Akt and Erk1/2 phosphorylation in exosomes-stimulated HUVEC cell (Corrado et al, 2012), targets the tumors and mechanisms that may induce drug resistance or interfere with the antitumor activity.
The timing and duration of the CTO therapy may be determined to be from the start of the chemotherapy and/or targeted therapy or at various stages during the therapeutic regimen based on the understanding of the dynamics and extent of the effect of the chemotherapeutic and/or targeted drugs over expression and amplification of oncogenes or development of new mutations. Current principles guiding the selection of chemotherapeutic and/or targeted drugs do not consider their impact on oncogene amplification and new mutations that follow after a few courses of successful initial effective regimens. As a result it is only after the targeted cancers cease to respond and progress that other rescue drugs are tried, as a last resort. It is important to plan ahead and prevent the development of resistance in early stages, and also in later stages when cancers have become refractory to initial therapy with TKIs. However, the area of cellular signaling pathways of target kinases is poorly understood. This is why CTO, a multiple TKI in multiple tumor targets (and TKIs heretofore, not identified of understood but responsive to CTO) potentially provides a much needed method for cancer therapy in newly diagnosed and refractory cancers.
According to the method of the invention, it is 1) necessary to identify the genomic expression of a tumor, 2) to identify a profile of molecular targets in the tumor and select the appropriate targeted therapy and review from clinical literature and case studies whether to expect acquired resistance due to over expression of oncogenes or new mutations to potentially interfere with its anticancer activity, and 3) to select the most suitable combinatorial regimen of the cytotoxic drug, targeted therapy and CTO as part of an optimum therapeutic regimen. Among the problems currently associated with the use of cytotoxic and targeted drugs to treat cancers are the failure of targeted therapy after initial response, such failure resulting in progression of disease, and such failure likely caused by acquired resistance due to over expression of oncogenes and/or new mutations caused the therapy.
The combination of a cytotoxic drug with or without a targeted drug in addition to the multiple TKI, CTO thus provides more effective and sustained therapeutic paradigm for successful cancer treatment programs, a fundamental object of the invention.